By Jeanne DuPrau
The only city these children have ever known is going dark, its lights failing and its food running out, and two of them go looking for a way out.
Ember is a city of lamplight in the middle of endless darkness, and it is the only world Lina and Doon have ever known. But the great lights are starting to flicker, the storerooms are emptying, and the grown-ups in charge either cannot fix it or will not admit how bad it has gotten. When Lina finds a water-stained scrap of paper that might be a set of instructions for getting out, she and Doon start racing to piece it back together, before the lights go dark for good.
This is the rung where the science fiction gets bigger and stranger, and yet it is still built around two ordinary children and a puzzle they can actually solve. The idea underneath is a real and haunting one, a city built to keep people alive that was only ever meant to last so long, and DuPrau lets your child work it out right alongside Lina and Doon, clue by clue. It is tense and atmospheric without tipping into scary, and it ends on a note that pulls straight through into the next book.